The best kind of loam for every purpose in connection with
mushroom-growing is rich, fresh, mellow soil, such as florists eagerly
seek for potting and other greenhouse purposes. In early fall I get
together a pile of fresh sod loam, that is, the top spit from a pasture
field, but do not add any manure to it. Of course, while this contains a
good deal of grassy sod there is much fine soil among it, and this is
what I use for mushrooms. Before using it I break up the sods with a
spade or fork, throw aside the very toughest parts of them, and use the
finer earthy portion, but always in its rough state, and never sifted.
The green, soddy parts that are not too rough are allowed to remain in
the soil, for they do no harm whatever, either in arresting the mycelium
or checking the mushrooms, and there is no danger that the grass would
grow up and smother the mushrooms.

Common loam from an open, well-drained fallow field is good, and, if the
soil is naturally rich, excellent for any purpose. But do not take it
from the wet parts of the fields. Reject all stones, rough clods,
tussocks, and the like. Such loam may be used at once.

Ordinary garden soil is used more frequently than any other sort, and
altogether with highly satisfactory results. The greatest objection I
have to it is the amount of insects it is apt to contain on account of
its often repeated heavy manurings.

Roadside dirt, whether loamy or gritty, may also be used with good
results. If free from weeds, sticks, stones and rough drift, it may be
used at once, but it is much better to stack it in a pile to rot for a
few months before using.

Sandy soil, such as occurs in the water-shed drifts along the roads and
where it has been washed into the fields, is much inferior to stiffer
and more fibrous earth.

I have used the rich dark colored soil from slopes and dry hollows in
woods, and, odd though it may appear, as mushrooms do not naturally grow
in woods, with success. But it is not as good as loam from the open
field.

Peat soil or swamp muck that has been composted for two or three years
has failed to give me good returns. The mushrooms will come up through
it all right, but they do not take kindly to it.

Heavy, clayey loam is, in one way, excellent, in another, not so good.
So long as we can keep it equably moist without making it muddy it is
all right, but if we let it get a little too dry it cracks, and in this
way breaks the threads of the spawn